Abstract:
PROBLEM TO BE SOLVED: To more easily provide a voltage controlled oscillator having high linearity of oscillation frequency over a wide control potential range. SOLUTION: The voltage controlled oscillator comprises an inductor circuit, n variable capacitance circuits and a negative resistance circuit that are connected in parallel, and a reference voltage generation section 114 for generating n reference voltages based on a power supply potential. One of the n reference voltages is input to one of the terminals of a variable capacitance element of each of the n variable capacitance circuits. A control voltage Vt for feedback-controlling an oscillation frequency is input to the other of the terminals of the variable capacitance element of each of the n variable capacitance circuits. A first to a third reference voltage Vref1, Vref2 and Vref3 are input to a first to a third variable capacitance circuit A, B and C, respectively. The first to third reference voltages Vref1, Vref2 and Vref3 each have a fixed value, and a difference between the first reference voltage Vref1 and the second reference voltage Vref2 and a difference between the second reference voltage Vref2 and the third reference voltage Vref3 are different from each other. COPYRIGHT: (C)2009,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit for communication, wherein oscillating is enabled over a wide frequency range and selection of a band to be used of an oscillation circuit for transmission can be completed in a short time, even in a case that an oscillation circuit constituting a PLL circuit for transmission is formed on one semiconductor chip together with an oscillation circuit constituting a PLL circuit for reception and with an oscillation circuit for an intermediate frequency. SOLUTION: The oscillation circuit (TXVCO 240), constituting the PLL circuit for transmission, is constituted so as to be able to operate in a plurality of bands. A counter (32) for measuring the oscillation frequency of the oscillation circuit constituting the PLL circuit for transmission and a register (37) for storing measured result are arranged. A band, to be used for the oscillation circuit constituting the PLL circuit for transmission, is determined, on the basis of values for setting oscillation frequency of the oscillation circuit (RFVCO 250), constituting the PLL circuit for reception and for setting the oscillation frequency of the oscillation circuit (IFVCO 230) for the intermediate frequency, and the stored measured result. COPYRIGHT: (C)2004,JPO
Abstract:
PROBLEM TO BE SOLVED: To provide a voltage-controlled oscillator which prevents CN characteristics and linearity from deterioration, while making an oscillation frequency band broad-banded. SOLUTION: The voltage-controlled oscillator is constituted of an oscillating portion 23 and a control portion 28. The oscillating portion 23 outputs an output signal f vco of the oscillation frequency based on a control voltage VT and is provided with a switching means, to switch the oscillation frequency band of the output signal f vco based on an input of a switching signal VSW. The controlling portion 28 outputs the switching signal VSW, based on the control voltage VT. COPYRIGHT: (C)2004,JPO